The present invention relates to prime movers, and, more particularly, to a prime mover which converts tidal currents into power.
Ocean tides cause the displacement of millions of tons of water each day. As is well known, movement of water can be converted into usable power, and thus, tidal currents represent a vast source of power.
Devices are known which convert tidal currents into power. These devices usually comprise a turbine positioned so that water moving in response to the tide impacts the turbine to turn it. The turbine rotation is then translated into electric power.
As used herein, an overflow turbine is one in which the turbine wheel is turned in response to fluid flowing over the top of a turbine, and an underflow turbine is one in which the wheel is turned in response to fluid flowing underneath the turbine.
If the turbine is an overflow type, the turbines of known devices are fixed to a support, and the device forms a wall which must be very high to be profitable. Such high walls are expensive to manufacture and erect, are subject to damage from ocean storms, unduly disrupt normal ocean movements, detract from the esthetics normally associated with tidal waters or the like.
Other devices place the turbine on a floating platform which follows the movement of the water as it rises and falls.
However, the floating devices are susceptible to damage and/or breakup due to wind forces or high wave conditions. Furthermore, because the platform must float on the surface, the turbine must be an underflow type. Thus, water can only flow underneath the turbine to impulse it and the turbine is less efficient then the overflow type. Thus, devices using floating platforms must also be quite large to be profitable.
Furthermore, most known devices are unitary, that is formed of a single wall or supporting structure. Thus, each device must be specially made for a particular application. This customizing represents a costly process which essentially eliminates any possibility of mass producing the devices or their component parts.
The present invention is modular and converts tidal currents into electric power using a vertically movable overflow type turbine.